/Engine/Source/Runtime/Renderer/Public/VT/VirtualTextureFeedbackBuffer.h
Initialize for a "2D" buffer. Pass in view rectangles that define some subset of the buffer to actually analyze.
void Init2D ( FIntPoint InUnscaledBufferSize, [TArrayView](API\Runtime\Core\Containers\TArrayView)< FIntRect > const & InUnscaledViewRects, int32 InBufferScale )